Signal reproducing means



Fb- 4, 1941 w. c. WELLMANN 2,230,855

5mm. REPRODUGI'NG MEANS Filed March 15, 1939 Patented Feb. 4, 1941 2,230,855

UNITED STATES PATENT OFFICE SIGNAL REPRODUCING MEANS Walter C. Wellman, Riverside, Ill.

Application March 15, 1939, Serial No. 261,974

17 Claims. (Cl. 179-100.11)

This invention relates to signal reproducing guished from a purely mechanical or vibratory and transmitting circuits for any electrical or recording without electricity, such as a phonoelectronic use or a sound adjunct for radio for graph or graphaphone record in tablet, disc, or reproducing and projecting or transmitting recylinder form, and to recorded audible or sound corded audible or visual signals or whereby sigsignals, or visual signals, either alone or both in` nals or sound with or without pictures is repxocombination with other instrumentalities and duced and amplied, such as by means of a talkespecially involving an electronic or electrical ing picture machine or a moving picture machine use and Where electricity or magnetic energy is with sound on iilm or sound track film in comused as an intermediary or means to effect such bination with or as an adjunct to a radio receiver recording and reproduction and transmission 10 by direct connection thereto or by pick-up to rewithout the extensive equipment now used in reproduce the signals economically without hum production and transmission of audible or visual at the loud speaker, with more amplification and signals or both. less light source although adapted for application Another object of the invention is that by the to other methods of similar sound recordation use of direct current on the iilaments of all tubes,. l5

and reproduction, especially electrically as disas well as the exciter lamp, hum and unnecessary tinguished from purely mechanically as from a noises occasioned by alternating current, are phonograph record, in the form of a permanent eliminated, thereby resulting in greater eiiiciency or other sound record, recording means or methfor the entire unit. od, such as a sound track on a lrn with or with- Another object of the invention is to take aud-.1 20 out pictures, magnetic strip, tape, wire or the like. ible and visual signals or either, recorded elec- The invention consists in a combination of a trically as on a lm, magnetic strip or tape or recorded signal transmitter circuit with a radio the like, and reproduce the same as by means of receiving set, especially superheterodyne sets, a photo-electric sound pick-up employing a phowhereby electrical current or energy taken by izo-electric tube or light sensitive cell and inv 25 plugging into the house wiring on either direct or which the same is associated with a radio receivalternating currentmay be employed with the ing set or receiver, in which the output from the signal or sound reproducing circuit of audible reproducer of the recorded signal or sound oscilsignals or sounds, or visual signals or both; for lations will be detected and by direct electrical amplifying and economically reproducing the sigconnection or pick-up with the receiver, faith-y nais, sounds or any reproduction from a record, fully and economically reproduced and transespecially one electrically produced independentmitted fOr DIOdllCtiOIi 01 DIOGCOII by the 180- ly of or in combination with light such as a sound trical apparatus such as by the receiving set, the track of a lm or the like with or without picsignal waves transmitted by the carrier waves tures, such as talking pictures. having substantially the same characteristics as.

Another object of the invention is to provide such waves ordinarily received on an aerial or means of compensating for any loss or high or antenna of a radio receiving set, so as to permit low notes in a resistance coupled amplifier. selective detection of said reproduced recorded Another object of the invention is the use of Signals and mOdulaiiOn 0f the high 01 10W fredirect current in the exciter lamp used in said (111611037 Waves fIOm the reproduce? and 3150 1081-` unit, or any similar device using an exciter lamp mitting the economical use of either direct or in connection with a photo-electric cell for the alternating Currentreproduction of signals, thereby eliminating the Another object is whereby the foregoing advantransmission of hum from the exciter lamp to ytages may be obtained Without the use of aniT the photo-electric cell yand through the entire ranSfOImeI'S. 45

circuit, in a combination of electrical elements Other objects of the invention are to provide for reproducing recorded signals especially eleca modulating System in i116 CiI'Cilii @Specially tricany recorded signals or where e1ectric1ty is Aadapted for the reproduction and transmission used as an instrumentality for recording the of recorded signals such as sound on film; to prosame, particularly in the form of a permanent or vide crackle and hum-free reproduction for radio relatively permanent record or otherwise so long sets, to flatten or render more uniform the overas the signals, either audible or visual signals or all frequency response of the signals or sound both in combination such as sound on film with waves and to make possible the use of more amor without pictures, a magnetic impression or replication and less light in the exciter lamp used cording pattern, record or otherwise, distinin conjunction with a photo-electric cell. .55

Another feature is to provide a novel audible or visual signal or sound circuit using either direct or alternating current, to be used in connection with a radio receiver in the projection of pictures for home or other use employing a film having a sound track, the device being adapted to be connected with the house wiring and employing a single or two coupled rectifier tubes in conjunction with an oscillating unit and a lter choke and a double point double throw switch which is moved into one position for heating or starting the unit and in another position for direct current operation from the current flowing through.

Other objects and advantages will appear hereinafter and be brought out more fully, reference being had to the accompanying drawing, wherein:

Fig. 1 is a diagrammatic View of a circuit arrangement embodying the features of the invention and showing the receiver set directly connected to detect the audio waves; and

Fig. 2 is a fragmentary view of an alternate form of connection with a radio receiver detecting the low frequency audio waves carried and transmitted by the high frequency carrier waves of the circuit as a pick-up from an antenna.

Referring to the drawing, I designates a plug adapted to be connected to an ordinary wall socket of the house Wiring for supplying current, the same being connected by a lead wire 2 to a resistor 3 which may be variable if desired. The respective electrical Values of the elements of this circuit are designated adjacent thereto, by way of example, especially in connection with the equipment designed for home or local use and as explanatory thereof.

This resistor is connected to a contact 4 of a double pole double throw switch 5, one terminal of the switch being connected by a lead 6 to a conductor 'I and then through the heating filament of one or more rectifier tubes. As shown, the lead is taken through the filaments of two rectifier tubes 8 and 9 connected in series as shown and then to a resistor I0. Connection is then made at II back to the switch 5 through a contact I2, constituting the other pole of the blade or knife of the switch opposite that from which lead 6 extends, and through a contact I3 opposing the contact 4, to a junction i4 to the filament I5 of an oscillator or oscillation unit shown as a screen grid tube, it being understood that all of said tubes, heretofore referred to may be of any preferable type. Connection is then made in series to the heating filament of an amplifier tube, one or more of which can be used. As shown, connection is made to filaments I6 and I'I of two amplifier tubes and then through the lead I8 from the filament II to the ground I9 and a suitable control switch 25 back to the source at the plug I.

The wire 22a is connected to a contact 2I of the switch 5 opposite the contact 4 with an interposed filter choke 22 arranged and connected, as will be later described. The other contact 23 of the switch 5 opposite the contact 2| is connected to an interposed filter condenser 24 applied to the circuit and operated when the blade of the switch 5 spans or engages the contacts 2| and 23.

An exciter lamp 25 is directly connected with the resistance I0 and the contact I2 on one side at the junction II and with the filament I5 of the oscillator and contact I3 on the other side. This short circuits the exciter lamp when switch 5 is in the heating circuit so that the exciter lamp will not burn out with the heating circuit surge. This exciter lamp is employed in connection with a condenser lens or lens system 26 through which the light from the exciter lamp passes and it in turn throws a very narrow beam of light on the sound film 2?, that is, a film with a sound track or sound on nlm which may be combined with a picture film. The sound film is shown passing around the usual guide or gate, and window and a light sensitive cell or photo-electric tube 2G. Light passes through the film 2'I allowing the film to modulate the light, and the modulated light falling on the photo-electric cell 28 produces an alternating current exactly similar to the original sound on the film. This is in turn impressed on the grid 29 of the amplifier tube nearest thereto, having the filament I l, through a condenser' resistor network A, the purpose of which is to compensate for any lack of low or high notes in the original recording. This network includes a resistance 30 of suitable resistance to lower the overall gain to a desirable point connected to the photo-electric cell 28 with a series condenser 3| of such value as to pass all useful frequencies without attenuation, and having connected thereto in parallel, on the outside of the resistance 30 and condenser 3I, a low-capacity condenser 32 of suitable value to reduce the reactance above a suitable reference frequency, decreasing in reactance the higher the frequency. This allows an increasing frequency characteristic for the high frequencies to the point where the grid cathode and plate cathode capacities prevent any further increase in high response. The loW notes below a suitable reference frequency are adjusted by the increased reactance of a resistor capacity network B including a medium capacity condenser 33 which is connected between the condenser resistor network or unit A on one side, and the grid 29, directly to the cathode of the amplifier tube of the latter, with an interposed resistance 34 as will be more fully described. The condenser 33 is interposed between the resistance 34 and a resistance 35. Condenser 33 is in effect in parallel with the resistor 35 and a resistance 35 and a condenser 31 are interposed in the connection to the cathode. The first vacuum tube amplifier 38 having the filament I'I and the control electrode or grid 29 is connected through its anode plate 39 with a similar' resistor network C corresponding to condenser resistor network A and the resistor network B or unit just described. Resistor network unit C includes a condenser 45, condenser 4I, resistance 42, all in parallel with the circuit. Resistances 43, 43a, 44, and 44a, and a condenser 45 are connected to the control electrode or grid 46 of a second vacuum tube ampliiier 41 which latter is connected with the amplifier tube 38. The filaments I6 and I1 constituting the heating elements thereof, are connected in series. The current is then passed through a conventional resistor network D including a condenser 48 and resistors 49, 55 and 5I of suitable resistance or reactance and as previously pointed out, all or any of which may be variable, if desired.

There is also a resistance 52, connected to the cathode of tube 4l, corresponding to the resistance 3S, and another resistance 53 is connected to the cathode 55 of an oscillator tube 54 constituting part of the oscillation unit E which receives the amplified current from the tubes 38 and 41. The oscillator tube 54 may be in the form of a heptode tube and has one grid 56 thereof connected to the amplifier 41 through the condenser 48. The grid 51 is connected through a variable condenser 58 with an inductance 59 in parallel and an anode inductance 68 which is connected to the anode plate EI of the oscillator tube 54 for the development of radio frequency oscillations which are modulated by the previous amplifier and picked-up by a radio as designated at 62 or with an antenna 63 having an interposed condenser 64 as a safety precaution. This antenna produces vibrations in the ether which can be received by a radio without direct connection thereto and spaced at a distance therefrom. The screen grid 65 of the oscillator tube 54 is connected to the plate supply through a resistor 65 which is by-passed by a condenser 61 to ground 68. The inductance 59 having the variable condenser 58 connected thereto is also connected to another resistance 69 and a condenser 10 connected in parallel and in turn connected to ground I9.

The contacts 2| and 23 are connected through a condenser unit E with the ground I9. The return wires of the circuits leading from the various resistances are connected with another resistance 1I also connected to ground through a condenser unit G interposed in the circuit including the amplifier tube 41 while another condenser unit H is connected to the ampliiier tube 38. A resistance 12 is connected to the lead from the photo-electric tube having connection with the control electrode or grid 29 thereof and to the cathode 13 thereof with an interposed condenser 14 and condenser unit B corresponding to the aforesaid condenser units including the elements 33, 34, 35, 35 and 31 previously described. The cathode of the photo-electric cell or photoelectric tube is thus directly connected to the 'cathode of the rst amplifier tube instead of through a resistance and condens-er network as used in connection with conventional circuits through ground. This has the advantage of reducing hum and increasing efficiency. Connection is also made througha resistance 15 with an adjustable resistance 16 on either side of the connection with the condenser unit G and a resistor 11 from which connection is made through a resistor 18 with ground 19.

Interposed in the circuit to the exciter lamp is an adjustable resistance 83 serving the purpose of a rheostat to vary the intensity of the lamp, thereby varying the signal volume.

An ordinary radio receiver is also illustrated at 62 as heretofore described, the same being preferably of the heterodyne type with a plurality of stages of amplification, as including a plug 90 for connecting to the house wiring. However, as previously explained, instead of 'the physical connection or mutual indu'ctance permitting the elements to be plugged one into the other, the audio waves may be detected and picked up by means of the usual aerial or antenna from that of the signal reproducer and transmitter to reproduce and transmit signals. While particularly explained in connection with audible signals or sound, it is to be understood that the principle is capable of application for all signals and particularly those reproduced from an electrically recorded record such as sound on film and adapted for any electronic use.

Thus, in the operation of the circuit in the application of D. C. on the filaments, starting at the plug I, electrical current flows along the lead 2 to the resistor 3. This resistor makes up the difference in Voltage between the D. C. output of the rectiiier tubes 8 and 9 and the line voltage. The current continues along into contact 4 and through switch 5 and lead 6 to 1 and from 1 through the filaments 8 and 9 of the rectifier tubes to the resistor I0 which reduces the voltage to the required Voltage of the balance of the tubes and other load in the circuit. Continuing to the point I I, the current from there is led back to the contact I2 of the switch 5 and through the contact I3, when the switch is in the up or heating position, to the junction I4 leading to the filament I5 of the screen grid tube or oscillator unit 54, to filaments I6 and I1 directly through lead I8 to` the ground I9 and through control switch 20 to the source or plug I connected to the house wiring or otherwise. This represents the starting procedure of one embodiment of the application of the invention heretofore described. After reasonable time for the heating of the filaments 8, 9, I5, I6 and I1, the switch 5 is thrown in the opposite position to engage the contacts 2| and 23, which is the D. C. position. The current now flows through the tubes of the filaments 8 and 9, appearing at 1 as a pulsating D. C. current and then flowing through the switch 5 and contact 2| and through the choke 22 to the various parts of the circuit as already described. The filter condenser 24 connected to the Contact 23 and, in the form of the unit H is applied to the circuit to smooth the D. C. pulsations appearing across the exciter lamp 25 of tube filaments.

The light from the exciter lamp 25 passes through the condenser lens or lens system 2S which in turn throws a very narrow beam of light on the sound film 21. This light passing through the film 21 allows the film to modulate the light and the modulated light falling on the photo-electric cell 28 produces an alternating current exactly similar to the original sound on the film, and is impressed on the grid 29 through the condenser resistor network A, the purpose of which is to compensate for any lack of low or high notes in the original recording which it does in this manner. The audio frequencies are reduced to a certain proportion of their original amplitude by the resistance 38, condenser 3| being of such Value as to pass all useful frequencies without attenuation. Condenser 32 is a suitable value to reduce the reactance above a suitable reference frequency, decreasing in reactance, the higher the frequency. This allows an increasing frequency characteristic for the high frequencies to the point where the grid cathode and plate cathode capacities of the amplifier tubes prevent any further increase in high response. The low notes below a suitable reference frequency are adjusted by the increasing reactance of the condenser 33 so that the effective value of resistor 35 increases with the increasing reactance of condenser 33. The current is then amplified by the rst vacuum tube 38 and is passed through a similar resistance network C corresponding to the resistor network A, to the second vacuum tube 41. The currenlt is passed through a conventional resistor network D to the Oscillator tube 54 in which the radio frequency is modulated. These radio frequency oscillations may then be transmitted to the radio receiving set by an antenna or by a direct wire from the oscillator to the radio set as already described,

or by the use of alternating or direct current light power supply lines.

From the foregoing, there will be observed that with the signal reproducing and transmitting circuits or a sound adjunct combined with sound on film or other electrically produced or recorded record such as light produced vibrations, for radio receiving sets herein disclosed for reproducing and projecting or transmitting recorded audible or visual signals .or whereby signals or sound with or without pictures is produced and amplified for any electrical use, such as by means of a talking picture machine or a moving picture machine with sound on film or sound track film in combination with or as an adjunct to a radio receiving set by direct connection thereto or by pick-up to reproduce the signals economically without hum at the loud speaker, with more amplification and less light source, if possible. However, although the equipment is adapted for application to other methods of signal or sound recordation and reproduction, especially electrically as distinguished from purely mechanically produced records such as a phonograph record. An important feature is the use of the equipment and circuit in connection with the sound track of a film or using the light passing through the film to modulate the light falling on the photo-electric cell to produce an alternating current corresponding to the original sound on the lm and then amplifying and modulating radio frequency oscillations and the modulated output including the high frequency carrier waves and the low frequency audio waves which are picked up on the radio.

The normal circuit or circuits employed and the combination of a recorded signal transmitter circuit for reproducing signals particularly by light or sound on film and the amplifying and rectifying circuit employed whereby the equipment may be plugged into the ordinary line voltage of the house wiring or otherwise on either direct or alternating current and receiving such signals within the audible hearing range on an ordinary receiver preferably of the heterodyne type is of particular advantage. By this means, the signals of the signal or sound reproducing circuit will be received and amplified as well as economically reproduced in such a way as to eliminate the necessity for a high powered audio amplifier and complicated and expensive equipment ordinarily required. Moreover, while one electronic use is shown, it is to be understood that the invention embraces the circuits and arrangments or combinations for other electrical uses where electricity or magnetic energy is used as an intermediary or means to effect such reproduction or transmission of signals either audible or visual or both. The apparatus will be simple, inexpensive and embodied in small units capable of being readily transported or moved from place to piace and constitutes an important adjunct in a home or wherever it is desired to reproduce certain signal records as desired. Moreover, the signals will be free of hum, crackling sounds or other interference and render possible the use of more amplification with less light source and current consumption.

Any suitable tone control means may be employed or inserted in the circuit. In addition, by my circuits and arrangement or equipment, the equipment required for radio reception and also as distinguished from pure audio transmission without radio reception is reduced more than one-half and the weight thereof is also reduced at least one-half.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, these are capable of variation and modification without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electrical impulses, means for amplifying and modulating said impulses and including a resistor condenser unit and amplifying tubes in circuit therewith, and means for reducing hum in said circuit free of direct connection with ground by direct connection of the cathode of the translating means to the cathode of the amplifying tubes.

2. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electrical impulses, means for amplifying and modulating said impulses and including a condenser and resistor network and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electrical impulses, a photo-electric cell and an amplifier tube having its cathode directly connected to the cathode of the photo cell.

3, Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, means for amplifying and modulating said impulses, and including a low capacity condenser and amplifying tubes in circuit therewith,

means for reducing hum in said circuit free of Y.

direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electrical impulses, a photo-electric cell, other means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the nlm, means for converting the audio frequencies produced thereby into radio frequencies and means for transmitting and detecting said radio frequencies and reproducing the same.

4. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, means for amplifying and modulating said impulses, and including a low capacity condenser and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a

photo-electric cell, additional means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the lm, means for converting the audio frequencies produced thereby into radio frequencies, means for transmitting said radio frequencies, and a radio set for detecting and reproducing the same.

5. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, means for amplifying and modulating said pulses, amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photo-electric cell, cathode connected means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the film, means for converting the audio frequencies produced thereby into radio frequencies, means for transmitting said radio frequencies, and means for preliminarily heating the converting means and thereafter passing said current into the modulating and amplifying elements after the converting means has been heated.

6. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses,means for amplifying and modulating said impulses, and including a series parallel condenser resistance network and amplifying tubes in circuit'therewith, means for reducing hum in said circuit free of direct connection with ground,` said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photo-electric cell, preheating means for rectification to pass D. C. to the circuit and eliminate hum, means vfor amplifying and' modulating the pulsations thus produced from the sound vibrations on the film, means for converting the audio frequencies produced thereby into radio frequencies, means for transmitting said radio frequencies, means for taking current at line voltage and supplying D. C. current into the modulating, amplifying and converting elements and passing said current through a resistance to the exciter lamp, and means for initially regulating the current passing to the exciter lamp to vary the intensity of the lamp and the signal volume thereof.

'7. In a signal or sound reproducing means, a light effected record, means for passing light through said record for modulating the same, a light sensitive cell receiving said light toy produce an alternating current corresponding to the film record, means including ay condenser resistor network from said alternating current, an amplifying tube receiving the modulated light impulses, additional amplifying and modulating means, filter means, condenser means, means for receiving audio frequencies therefrom to produce radio frequencies, means for modulating said radio frequencies, transmitting and detecting the same, and means for initially passing D. C. current for preheating the filaments of rectifier tubes on direct current and thereafter said current through the plates of said tubes and into the circuit to eliminate hum through the whole circuit, including the exciter lamp.

8. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electrical impulses, means for amplifying and modulating said impulses and including a condenser and resistor network including a low capacity condenser and a conventional condenser and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electrical impulses, a photo-electric cell and an amplifier tube having its cathode directly connected to the cathode of the kphoto cell.

9. Signal reproducing means including an electrically produced record of signals, means for -translating `the vibrations thereof to electric impulses, means for amplifying and modulating said impulses, and including a medium capacity condenser and a resistance, and a low capacity condenser and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photo-electric cell, additional means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the film, means for converting the audio frequencies produced thereby into radio frequencies, and means for transmitting said radio frequencies.

l0. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, meansfor amplifying and modulating said impulses, and including a condenser and resistor series and a condenser in parallel therewith and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connectionWithfground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photo-electric cell, additional means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the films means forl converting the audio frequencies produced thereby into radio frequencies, and means for transmitting said radio frequencies.

1l. Signal reproducing means including an electrically produced record of signals, means for` translating the vibrations thereof to electric impulses, means for amplifying and modulating said pulses, amplifying tubes in circuit therewith, means for reducing hum. in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photoelectric cell, cathode connected means to eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the film, means to convert said impulses into audio frequencies, means for converting the audio frequencies into radio frequencies for transmission, said converting means including one or more rectifier tubes and means for passing A. C. to the filaments of the rectifier tubes to heat the same and thereafter rectify A. C. to hearl all filaments and feed other loads in the circuit with D. C.

12. In signal reproducing means, a light affected record, a photo cell, an exciter lampto pass light through the record to the photo cell, means including an A. C. current supply, rectifying tubes, means for optionally shunting D. C. current to the filaments of said rectifying tubes to preheat the same prior to passing rectified current to the circuit and to pass D. C. to the exciter lamp, a resistance in the circuit to the exciter lamp, an adjustable resistance in said circuit and means to convert the vibrations thereof from electric pulses into radio frequencies.

13. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, means for amplifying and modulating said impulses, and including a low capacity condenser in parallel with a condenser and resistance in series and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit operating on D. C. for translating the vibrations into electiic impulses, a photo-electric cell, filament preheating means for rectification to pass D. C. to the circuit and eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the record, means for converting the audio frequencies produced thereby into radio frequencies, means for transmitting said radio frequencies, means for taking current at line voltage and supplying D. C. current into the modulating, amplifying and converting elements and passing said current through a resistance to the exciter lamp, and means for initially regulating the current passing to the exciter lamp to vary the intensity of the lamp and the signal volume thereof.

14. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electric impulses, means for` amplifying and modulating said impulses, and including a series parallel condenser resistance network and amplifying tubes in circuit therewith, means for reducing hum in said circuit free of direct connection with ground, said means including an exciter lamp in the circuit for translating the vibrations into electric impulses, a photo-electric cell, preheating means for rectification to pass D. C. to the circuit and eliminate hum, means for amplifying and modulating the pulsations thus produced from the sound vibrations on the lm, means for converting the audio frequencies produced thereby into radio frequencies, means for transmitting said radio frequenciesy means for taking current at line voltage and supplying D. C. current to the load in the circuit.

15. In a. signal or sound reproducing means, a light effected record, means for passing light through said record for modulating the same, a light sensitive cell receiving said light to produce an alternating current corresponding to` the lm record, means including a condenser resistor network from said alternating current, an amplifying tube receiving the modulated light impulses, additional amplifying and modulating means, filter means, condenser means, means for receiving audio frequencies therefrom to produce radio frequencies, means for modulating said radio frequencies, transmitting and detecting the same, and means for feeding D. C. to the laments to pass D. C. to the circuit.

16. The combination with alight sensitive cell, an exciter lamp, and means to supply D. C. to the exciter lamp.

17. Signal reproducing means including an electrically produced record of signals, means for translating the vibrations thereof to electrical impulses, means for amplifying and modulating said impulses and including a resistor condenser unit and amplifying tubes in circuit therewith, a

cathode of the translating means being directly Y connected with the cathode of at least one amplifying tube and said connections being independent of connection through aresistance and condenser to ground.

WALTER C. WELLMAN. 

